The present invention relates to the medical imaging arts. It particularly relates to the measurement of aneurysms and planning for surgical replacement thereof by synthetic stents using image data generated by multiple-slice computed tomography (CT), and will be described with particular reference thereto. However, the invention will also find application in conjunction with other imaging techniques such as magnetic resonance-based imaging (MRI) or nuclear medicine, as well as in acquiring and analyzing data which is useful for other types of medical procedure planning.
The development of multi-slice CT systems having increasingly improved resolution particularly in the slice-direction is making CT imaging of vascular systems attractive for clinical applications such as the discovery of potentially life-threatening aneurysms and the precise measurement of such an aneurysm in order to design a synthetic replacement stent and plan the surgical implantation thereof. However, for CT to gain clinical acceptance in this area, reconstruction and post-processing of the images should be automated to the greatest extent possible. Automation becomes increasingly important with multi-slice CT because of the much greater amount of data (i.e., number of slices) produced by the instrument.
Currently, imaging analyses for identifying and measuring aneurysms are cumbersome and laborious. Prior art systems typically employ maximum intensity projections (MIPS) which lose much of the valuable three-dimensional information available from a multi-slice CT scan. These methods are usually manual, and do not provide for efficient workflow, operator guidance, or means for verifying the stent measurements.
The present invention contemplates an improved method and apparatus for semi-automatic aneurysm measurement and stent planning using volume image data which overcomes the aforementioned limitations and others.
According to one aspect of the invention, a method for tracking a blood vessel containing an aneurysm in a three-dimensional image is disclosed. A blood vessel type is identified. Vascular landmarks are received from an associated user. An orthogonal vessel plane is extracted. A vessel center is located in the vessel plane. Vessel edges in the vessel plane are fitted. The extracting, locating, and fitting are recursively repeated a plurality of times to track the vessel.
According to another aspect of the invention, a method for assisting an associated user in planning a stent replacement of a blood vessel in an associated patient is disclosed. A three-dimensional vascular image is acquired that includes imaging of the vessel to be replaced. The vessel to be replaced is tracked in the three-dimensional vascular image. The vessel tracking includes at least extraction of a vessel centerline and vessel boundaries. Stent parameters are measured based on the vessel tracking.
According to yet another aspect of the invention, an apparatus is disclosed for measuring parameters preparatory to a stent replacement of an aneurytic blood vessel in an associated patient. A computed tomography (CT) scanner acquires image data corresponding to multiple two-dimensional image slices. A reconstruction processor reconstructs a three-dimensional image representation from the image data. A tracking processor produces a tracked vessel including at least a centerline and selected vessel boundaries. A user interface displays a rendering of the image representation to an associated user, measures selected vascular parameters corresponding to the stent parameters, and graphically superimposes the measured parameters on the rendering of the image representation.
According to still yet another aspect of the invention, an apparatus is disclosed for measuring stent parameters preparatory to a stent replacement operation. A means is provided for acquiring three-dimensional image data. A means is provided for reconstructing the image data into a three-dimensional image representation. A means is provided for tracking the blood vessel to be replaced. The tracking includes at least estimation of a vessel centerline and selected vessel boundaries in three-dimensions. A means is provided for displaying a rendering of the image representation to an associated user. A means is provided for measuring selected vascular parameters corresponding to the stent parameters.
One advantage of the present invention is that it operates directly on the three-dimensional data and performs the tracking in 3-D.
Another advantage of the present invention is that it provides for measurement of both the true and the false lumen of an aneurysm.
Another advantage of the present invention is that the vessel branches are identified and optionally tracked for a pre-selected distance to ascertain that adequate stent-anchoring branch portions are available.
Yet another advantage of the present invention is that it facilitates stent measurements in accordance with the stent manufacturer""s specifications.
Still yet another advantage of the present invention is that it provides intuitive graphical feedback comparing the stent measurements and the stent structure with the acquired vascular images.
Numerous additional advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments.
The invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for the purpose of illustrating preferred embodiments and are not to be construed as limiting the invention.
FIG. 1 schematically shows an exemplary multi-slice CT imaging system that suitably practices an embodiment of the invention;
FIG. 2 schematically shows an exemplary method embodiment of the invention;
FIG. 3 shows a schematic of a AAA aortic aneurysm with user-selected landmarks superimposed;
FIG. 4 shows an exemplary user interface window for user selection of the stent type;
FIG. 5 schematically shows a suitable embodiment of the vessel center finder of FIG. 2;
FIG. 6 schematically shows a selection of rays for the central measure map calculation at a point (i,j);
FIG. 7 shows an exemplary central measure map;
FIG. 8A shows an initial dynamic contour spline or snake to be used to fit the true lumen;
FIG. 8B shows the fitted dynamic contour spline or snake corresponding to FIG. 8A;
FIG. 9 shows an exemplary user interface for performing stent measurements and stent implantation planning in accordance with an embodiment of the invention;
FIG. 10 shows a suitable user interface for performing and verifying the stent measurements; and
FIG. 11 shows a suitable display of the stent structure superimposed on a vascular image.